ok so if it is the correct battery, there must be something causing a drain somewhere.. how long did you have the ammeter connected up? does it have a hold function? with mine i can set it to hold the highest reading

the 2 most common issues would be the alternator draining the battery or not charging the battery and i remember an issue with the stereo draining the battery as well to check the stereo assuming you have the radio code would be to pull the stereo fuse and see if the battery still drains depends on how good you are with electrics it can be what i said above or faulty ecu timer module not switching off permenantly engaged feul /diesel pump to name a few